Cortisone is a steroid that is often injected into joints to help reduce pain and swelling. This tends to work pretty well and there are rarely any significant side effects.
However, in side effect that can occur from cortisone shots is that they can thin out the skin, especially if the shots are given repeatedly in the same location. This can lead to a pale spot on the skin or even a sunken or dimpled area of the skin.
You can also develop some scarring at the site where the needle is inserted, which might cause a small raised bump. However, I am not sure what to make of multiple small bumps at the site. Therefore, I would recommend that you go to see your primary care doctor
about the issue (or whichever doctor performed the injection), just so that they can take a look and make sure that there is no serious problem.
Any joint injection is associated with a small risk of joint infection. Therefore if the skin overlying your ankle becomes swollen, warm, or red, those are serious warning signs of a potential infection and you would need to seek immediate evaluation by your doctor or in an emergency room.